Various types of machinery are used to handle documents. For example, mail-sorting equipment feeds mail through a system that evaluates routing information on the mail and sorts the mail based on the routing information. Computer printers and facsimile machines are also examples of machines that handle documents. The common function of these machines is that they must separate documents from one another, i.e. there must be a singulating function. For example, a stack of paper is inserted into a printer, then each sheet must be separated from the stack to utilize it in the machine. Similarly, a mail-sorting machine may take a stack of mail and process each mail piece individually, requiring the individual mail items to be separated from one another.
It is noted that “documents” is used herein in the broadest sense possible, and includes for example, paper, mail, magazines, booklets, folders and the like. Documents need not consist of paper only but may also consist of other materials such as for example woven materials, plastics or metal, either alone or in combination.
Reliable document separating devices often are cumbersome, such as those that contain vacuum mechanisms to effectuate separation of documents that vary in thickness, dimensions or material. Less cumbersome devices typically rely primarily on friction between the document and the separator. These devices may employ, for example, grinding stones, stationary belts or rubber wheels. Generally, the device is set for a particular document thickness. The setting is adjusted when documents of a different thickness are to be processed. Such devices, are not self-adjusting, so they cannot process a stack of varying thickness documents. Because they do not automatically adjust satisfactorily for varying document thickness, the coefficient of friction between the document and separator changes, thereby causing documents to be transported or fed through the system two or more at a time.
Accordingly, there is a need for a practical, reliable document separator to singulate documents, such as stacks of sheets of paper or mail of varying thickness.